/*
 * Copyright 2002-2016 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.beans.factory.xml;

import org.springframework.lang.Nullable;

/**
 * Used by the {@link org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader} to
 * locate a {@link NamespaceHandler} implementation for a particular namespace URI.
 *
 * @author Rob Harrop
 * @since 2.0
 * @see NamespaceHandler
 * @see org.springframework.beans.factory.xml.DefaultBeanDefinitionDocumentReader
 */

/**
1 作用
 用于解析命名空间URI并返回相应的NamespaceHandler实现。

2  方法
 NamespaceHandler resolve(String namespaceUri);
3 实现类
 DefaultNamespaceHandlerResolver: 默认的命名空间处理器解析器实现

4 和其他接口和类之间的关系
	 与 NamespaceHandler: NamespaceHandlerResolver负责定位和返回NamespaceHandler实例
	 与 DefaultNamespaceHandlerResolver: 默认实现类，通过读取META-INF/spring.handlers文件来解析命名空间处理器
	 与 DefaultBeanDefinitionDocumentReader: 使用NamespaceHandlerResolver来定位处理自定义命名空间的NamespaceHandler
	 与 XmlReaderContext: XmlReaderContext包含NamespaceHandlerResolver实例，提供给其他组件使用
5 总结
	 职责单一: 专门负责根据命名空间URI定位相应的NamespaceHandler
	 设计简洁: 作为函数式接口，易于实现和使用
	 松耦合: 将命名空间解析与具体实现解耦
	 可扩展: 允许自定义实现来满足特定需求


 */
@FunctionalInterface
public interface NamespaceHandlerResolver {

	/**
	 * Resolve the namespace URI and return the located {@link NamespaceHandler}
	 * implementation.
	 * @param namespaceUri the relevant namespace URI
	 * @return the located {@link NamespaceHandler} (may be {@code null})
	 */
	@Nullable
	NamespaceHandler resolve(String namespaceUri);

}
